Swab-Based Diagnostic Systems

ABSTRACT

A diagnostic test system for detecting the presence or absence of an analyte within a test sample is provided. For instance, the system may include a swab and a detection unit. The detection unit includes a first component that is capable of receiving the swab, the first component defining an insertion chamber within which a fluid is capable of being retained. The detection unit also includes a second component that defines a detection chamber within which an assay for detecting the presence or absence of the analyte is capable of being contained. The first component is rotatable relative to the second component from an inactive position to an active position. In the inactive position, the fluid remains substantially contained within the insertion chamber. In the active position, the fluid may flow from the insertion chamber to the detection chamber and contact the assay.

BACKGROUND OF THE INVENTION

Medical swabs are commonly used to collect biological specimens from apatient. Such medical swabs generally include a fibrous tip at one endof an elongated stick or shaft. Once a sample is collected, it may betransferred from the tip to a testing medium for performance of animmunoassay to determine the presence or absence of an analyte ofinterest. Some systems, known as “all-in-one” swab systems, have beendeveloped that provide both the reagents for the immunoassay and theswab in a single, self-contained apparatus. However, one problem withsuch “all-in-one” systems is that the fluid contained within theapparatus often leaks out of the apparatus prior to use. In addition,the method for using such devices typically involves several complicatedsteps that may lower the real-time efficacy of the device in detectingthe presence or absence of the analyte.

As such a need currently exits for a swab-based device that is effectivein detecting the presence of an analyte in a simple manner.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, a diagnostictest system is disclosed for detecting the presence or absence of ananalyte within a test sample. The system comprises a swab and adetection unit. The detection unit comprises a first component that iscapable of receiving the swab. In one embodiment, the first componentdefines a sample port through which the swab is capable of beinginserted. A hydraulic seal (e.g., o-ring) may form a sealing fit betweenthe sample port and the swab. The first component defines an insertionchamber within which a fluid is capable of being retained. In oneembodiment, a flexible packet is contained within the insertion chamber,the flexible packet being configured to retain the fluid. For example,the flexible packet may be formed from a film, metallic foil, orcombinations thereof. The flexible packet may have a thickness of lessthan about 0.05 inches, and in some embodiments, from about 0.0007inches to about 0.02 inches.

The diagnostic test system also comprises a second component thatdefines a detection chamber within which an assay for detecting thepresence or absence of the analyte is capable of being contained. Thefirst component is rotatable relative to the second component from aninactive position to an active position. In the inactive position, thefluid remains substantially retained within the insertion chamber. Inthe active position, the fluid may flow from the insertion chamber tothe detection chamber and contact the assay. In one embodiment, forinstance, the system further comprises a delivery channel that is alsorotatable relative to the second component. The second component maycomprise a connection channel, wherein the delivery channel is capableof rotation into fluid communication with the connection channel so thatthe fluid flows from the insertion chamber, through the deliverychannel, and into the connection channel. The connection channel may bein fluid communication with the detection chamber.

In accordance with another embodiment of the present invention, a methodis disclosed for detecting the presence or absence of an analyte withina test sample. The method comprises:

i) providing a diagnostic test system, the system comprising a swab anda detection unit, the detection unit comprising:

-   -   a) a first component that is capable of receiving the swab, the        first component defining an insertion chamber within which a        fluid is retained; and    -   b) a second component defining a detection chamber within which        an assay for detecting the presence or absence of the analyte is        capable of being contained;

ii) contacting the swab with the test sample;

iii) inserting the swab into the insertion chamber of the firstcomponent so that the swab contacts the fluid; and

iv) rotating the first component relative to the second component sothat the fluid flows from the insertion chamber to the detection chamberand contacts the assay. The method may further comprise determining theintensity of a detection signal generated at a detection zone of theassay, wherein the amount of the analyte within the test sample isdetermined from the detection signal. In addition, the detection signalmay be calibrated by a calibration signal generated at a calibrationzone of the assay, wherein the amount of the analyte within the testsample is determined from the detection signal as calibrated by thecalibration signal.

Other features and aspects of the present invention are discussed ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth more particularly in the remainder of the specification, whichmakes reference to the appended figures in which:

FIG. 1 is a perspective view of one embodiment of a diagnostic system ofthe present invention contained within a sealed package;

FIG. 2 is a perspective view of one embodiment of a diagnostic system ofthe present invention with the swab and test unit shown separately;

FIG. 3 is a perspective view depicting insertion of a swab into the testunit shown in FIG. 2;

FIG. 4 is a perspective view depicting rotation of the test unit shownin FIG. 2;

FIG. 5 is a cross-sectional view of the rotated test unit depicted inFIG. 4; and

FIG. 6 is a perspective view of an assay that may be utilized in oneembodiment of the present invention.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS Definitions

As used herein, the term “analyte” generally refers to a substance to bedetected. For instance, analytes may include antigenic substances,haptens, antibodies, and combinations thereof. Analytes include, but arenot limited to, toxins, organic compounds, proteins, peptides,microorganisms, amino acids, nucleic acids, hormones, steroids,vitamins, drugs (including those administered for therapeutic purposesas well as those administered for illicit purposes), drug intermediariesor byproducts, bacteria, virus particles and metabolites of orantibodies to any of the above substances. Specific examples of someanalytes include ferritin; creatinine kinase MB (CK-MB); digoxin;phenytoin; phenobarbitol; carbamazepine; vancomycin; gentamycin;theophylline; valproic acid; quinidine; luteinizing hormone (LH);follicle stimulating hormone (FSH); estradiol, progesterone; C-reactiveprotein; lipocalins; IgE antibodies; cytokines; vitamin B2micro-globulin; glycated hemoglobin (Gly. Hb); cortisol; digitoxin;N-acetylprocainamide (NAPA); procainamide; antibodies to rubella, suchas rubella-IgG and rubella IgM; antibodies to toxoplasmosis, such astoxoplasmosis IgG (Toxo-IgG) and toxoplasmosis IgM (Toxo-IgM);testosterone; salicylates; acetaminophen; hepatitis B virus surfaceantigen (HBsAg); antibodies to hepatitis B core antigen, such asanti-hepatitis B core antigen IgG and IgM (Anti-HBC); human immunedeficiency virus 1 and 2 (HIV 1 and 2); human T-cell leukemia virus 1and 2 (HTLV); hepatitis B e antigen (HBeAg); antibodies to hepatitis B eantigen (Anti-HBe); influenza virus; thyroid stimulating hormone (TSH);thyroxine (T4); total triiodothyronine (Total T3); free triiodothyronine(Free T3); carcinoembryoic antigen (CEA); lipoproteins, cholesterol, andtriglycerides; and alpha fetoprotein (AFP). Drugs of abuse andcontrolled substances include, but are not intended to be limited to,amphetamine; methamphetamine; barbiturates, such as amobarbital,secobarbital, pentobarbital, phenobarbital, and barbital;benzodiazepines, such as librium and valium; cannabinoids, such ashashish and marijuana; cocaine; fentanyl; LSD; methaqualone; opiates,such as heroin, morphine, codeine, hydromorphone, hydrocodone,methadone, oxycodone, oxymorphone and opium; phencyclidine; andpropoxyhene. Other potential analytes may be described in U.S. Pat. No.6,436,651 to Everhart, et al. and U.S. Pat. No. 4,366,241 to Tom et al.

As used herein, the term “test sample” generally refers to a materialsuspected of containing the analyte. The test sample may be useddirectly as obtained from the source or following a pretreatment tomodify the character of the sample. The test sample may be derived fromany biological source, such as a physiological fluid, including, blood,interstitial fluid, saliva, ocular lens fluid, cerebral spinal fluid,sweat, urine, milk, ascites fluid, mucous, synovial fluid, peritonealfluid, vaginal fluid, amniotic fluid or the like. The test sample may bepretreated prior to use, such as preparing plasma from blood, dilutingviscous fluids, and the like. Methods of treatment may involvefiltration, precipitation, dilution, distillation, mixing,concentration, inactivation of interfering components, and the additionof reagents. Besides physiological fluids, other liquid samples may beused such as water, food products and the like for the performance ofenvironmental or food production assays. In addition, a solid materialsuspected of containing the analyte may be used as the test sample. Insome instances it may be beneficial to modify a solid test sample toform a liquid medium or to release the analyte.

DETAILED DESCRIPTION

Reference now will be made in detail to various embodiments of theinvention, one or more examples of which are set forth below. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations may be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment, may be used on another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

Referring to FIGS. 1-2, for instance, one embodiment of a diagnostictest system 10 that may be formed according to the present inventionwill now be described in more detail. As shown, the system 10 includes aswab 20 and a detection unit 30 into which the swab 20 may be inserted.The swab 20 and/or detection unit 30 may optionally be sealed within apackage 40. The configuration of the swab 20 (e.g., shape, size,materials, etc.) may generally vary as is well known in the art. Forexample, in the illustrated embodiment, the swab 20 includes anelongated shaft 22 having a tip 24 of an absorbent material, such ascotton or rayon, at one end. It should be understood that the tip 24 mayalso be formed from any other absorbent material known in the art, andmay possess any desired shape and/or size. Further, any other swabconstruction, as well as any other type of test sample collectiondevice, may also be used in the present invention. For example, othertypes of test sample collection devices are described in U.S. Pat. No.6,541,194 to DiCesare and U.S. Pat. No. 6,548,018 to DiCesare, et al.,which are incorporated herein in their entirety by reference thereto forall purposes.

The detection unit 30 is generally of a size and shape to enable easymanual handling during use. In the illustrated embodiment, for example,the detection unit 30 is substantially cylindrical in shape and isformed from at least two components, i.e., a first component 32 in fluidcommunication with a second component 34. The first and secondcomponents 32 and 34 may be made from any of a variety of materials,such as molded or blown plastic. In addition, the first and secondcomponents 32 and 34 may also have a variety of different shapes and/orsizes. In the illustrated embodiment, for instance, the first component32 has a generally cylindrical shape defined by an enclosure 80 thatbegins at a generally circular lower portion 82 and ends at the sampleport 72, wherein the width (e.g., diameter) of the component 32 isgreater at the lower portion 82 than at the port 72. Similarly, thesecond component 34 also has a generally cylindrical shape defined by anenclosure 84 that begins at a generally rectangular upper portion 86 andends at the bottom end 88 of the detection unit 30, wherein the width ofthe component 34 is greater at the upper portion 86 than at the bottomend 88. The detection unit 30 has a length that allows the swababsorbent tip 24 to be fully immersed in the reagents involved, whichmay be determined by the amount of reagent that is required. Examplevolumes of the reagents are from about 50 to about 1000 microliters offluid, with a typical amount being from about 100 to about 200microliters.

The first component 32 defines a hollow insertion chamber 70 into whichthe swab 20 may be easily inserted via a sample port 72. The insertionchamber 70 may be provided with a fluid for mixing with a test samplecontained on the swab 20. For example, the fluid may be a buffer fluid,such as phosphate-buffered saline (PBS) (e.g., pH of 7.2) or2-(N-morpholino) ethane sulfonic acid (MES) (e.g., pH of 5.3). Othertypes of fluids that may be contained within the device includedetergents, salts, lysing agents (such as for detection of microbes,e.g., Strep bacteria or yeasts), blocking agents (e.g., bovine serumalbumin), other proteins, and so forth. Still other optional materialsthat may be present within the fluid include labeled microparticles,detection probes, dyes, electrochemically-active agents (e.g., redoxmediators), or other reagents used to create a signal for detection.

To inhibit leaking of the fluid from the sample port 72, variousmechanisms may be employed. For example, prior to insertion of the swab20, a top or cap may cover the sample port 72. In addition, the fluidwithin the insertion chamber 70 may also be retained within a thin,flexible packet (not shown) that is relatively resistant to diffusion ofthe fluid therethrough. The packet may be formed from a variety ofdifferent materials, such as nonporous films, metallic seals (e.g.,aluminum foil), etc. Some suitable materials used in the fabrication offilms for forming the packet may include thermoplastic polymers, such aspolyolefins (e.g., polyethylene, polypropylene, etc.), includinghomopolymers, copolymers, terpolymers and blends thereof; ethylene vinylacetate; ethylene ethyl acrylate; ethylene acrylic acid; ethylene methylacrylate; ethylene normal butyl acrylate; polyurethane;poly(ether-ester); poly(amid-ether) block copolymers; and the like.Other suitable materials may include non-thermoplastic materials,silicone-based materials, other elastomeric materials, and so forth. Insome embodiments, it is desired to minimize the thickness of the packetso that a user may easily rupture it with the swab 20. In suchinstances, the thickness of the packet may be less than about 0.05inches, in some embodiments between about 0.0003 inches to about 0.01inches, and in some embodiments, between about 0.0007 inches to about0.02 inches.

In addition, mechanisms may also be employed to inhibit fluid leakagefrom the sample port 72 after insertion of the swab 20 into theinsertion chamber 70. For example, as shown in FIG. 2, the firstcomponent 32 may utilize a hydraulic seal, such as o-rings 33 and 44. Asis well known in the art, the o-rings 33 and 44 provide a sealing fitbetween the outer surface of the swab 20 and the inner surface of thesample port 72. Other known hydraulic seals, such as t-rings, B-rings,v-rings, etc., may also be used in the present invention. Using suchseals, unwanted leakage from the sample port 72 may be inhibited.

As indicated above, the first component 32 is in fluid communicationwith a second component 34. In this embodiment, for example, the firstcomponent 32 generally rotates about a vertical axis A relative to thesecond component 34. Rotation may be accomplished manually, or throughany well known automated device known in the art, including well knownelectronics, timing circuitry, etc. Due to the relative rotation of thecomponents 32 and 34, a user may easily manipulate the components asdesired so that they are placed in direct engagement. Namely, thedetection unit 30 contains a delivery channel 38 that is also capable ofrotation about a vertical axis A, which is formed integral with orseparate from the first component 32. In the illustrated embodiment, forexample, the delivery channel 38 is connected to the lower portion 82 ofthe first component 32.

When not in use, the first component 32 and delivery channel 38 arepositioned so that fluid within the insertion chamber 70 does not flowto a detection chamber 73 of the second component 34, i.e., inactiveposition. In one embodiment, for instance, this prohibitive function isaccomplished by a barrier 36, which may have any suitable size and/orshape, and be formed from any suitable material known in the art. Forexample, in one embodiment, the barrier 36 is formed from aliquid-impermeable polymeric material. To engage the first component 32with the second component 34, the first component 32 is rotated so thatthe delivery channel 38 is positioned adjacent to a connection channel42 of the second component 34, i.e., active position. Consequently,fluid is capable of flowing from the chamber 70, through the deliverychannel 38 and connection channel 42, and finally into the detectionchamber 73.

Referring to FIGS. 3-5, the operation of the diagnostic test system 10will now be described in more detail. Initially, the tip 24 of the swab20 is contacted with a test sample suspected of containing the analyteof interest. Thereafter, as represented by the directional arrows ofFIG. 3, the tip 24 is inserted through the sample port 72. Uponinsertion, the o-rings 33 and 44 form a fitting seal around theelongated shaft 22 of the swab 20. As described above, insertion of thetip 24 may also cause a thin, flexible packet (not shown) within theinsertion chamber 70 to rupture, thereby releasing a fluid retainedtherein to mix with the test sample. Once the swab 20 is inserted andoptionally allowed to mix with a fluid within the insertion chamber 70,the first component 32 may then be placed into engagement with thesecond component 34. The engagement of the two components is illustratedin FIG. 4. Specifically, in this embodiment, the first component 32 isrotated in a counter-clockwise direction so that the delivery channel 38is placed into communication with the connection channel 42. In thismanner, fluid may flow from the insertion chamber 70 into a detectionchamber 73 of the second component 34. Once in the detection chamber 73,the fluid is allowed to contact an assay 60 for detecting the presenceor absence of the analyte of interest.

For purposes of illustration only, various examples of an assay 60 thatmay be used in conjunction with the diagnostic test system 10 will nowbe described in more detail. It should be understood, however, thatother assays are also contemplated by the present invention. In fact,the present invention is not limited to any particular assayconfiguration. In this regard, referring to FIG. 6, one embodiment of anassay 60 is illustrated that is an immunoassay. Immunoassays utilizemechanisms of the immune systems, wherein antibodies are produced inresponse to the presence of antigens that are pathogenic or foreign tothe organisms. These antibodies and antigens, i.e., immunoreactants, arecapable of binding with one another, thereby causing a highly specificreaction mechanism that may be used to determine the presence orconcentration of that particular antigen in a biological sample.

In the illustrated embodiment, the assay 60 contains a porous membrane63 optionally supported by a rigid material 61. In general, the porousmembrane 63 may be made from any of a variety of materials through whicha fluid is capable of passing. For example, the materials used to formthe porous membrane 63 may include, but are not limited to, natural,synthetic, or naturally occurring materials that are syntheticallymodified, such as polysaccharides (e.g., cellulose materials such aspaper and cellulose derivatives, such as cellulose acetate andnitrocellulose); polyether sulfone; polyethylene; nylon; polyvinylidenefluoride (PVDF); polyester; polypropylene; silica; inorganic materials,such as deactivated alumina, diatomaceous earth, MgSO₄, or otherinorganic finely divided material uniformly dispersed in a porouspolymer matrix, with polymers such as vinyl chloride, vinylchloride-propylene copolymer, and vinyl chloride-vinyl acetatecopolymer; cloth, both naturally occurring (e.g., cotton) and synthetic(e.g., nylon or rayon); porous gels, such as silica gel, agarose,dextran, and gelatin; polymeric films, such as polyacrylamide; and thelike. In one particular embodiment, the porous membrane 63 is formedfrom nitrocellulose and/or polyether sulfone materials. It should beunderstood that the term “nitrocellulose” refers to nitric acid estersof cellulose, which may be nitrocellulose alone, or a mixed ester ofnitric acid and other acids, such as aliphatic carboxylic acids havingfrom 1 to 7 carbon atoms.

The assay 60 may also contain an absorbent pad 68. The absorbent pad 68generally receives fluid that has migrated through the entire porousmembrane 63. As is well known in the art, the absorbent pad 68 mayassist in promoting capillary action and fluid flow through the membrane63. In some embodiments, the fluid from the connection channel 42 (seeFIGS. 1-5) may first contact a sample pad (not shown) that is in fluidcommunication with the porous membrane 63. Some suitable materials thatmay be used to form the sample pad include, but are not limited to,nitrocellulose, cellulose, porous polyethylene pads, and glass fiberfilter paper. If desired, the sample pad may also contain one or moreassay pretreatment reagents, either diffusively or non-diffusivelyattached thereto.

In the illustrated embodiment, the test sample travels from the samplepad (not shown) to a conjugate pad 62 that is placed in communicationwith one end of the sampling pad. The conjugate pad 62 is formed from amaterial through which a fluid is capable of passing. For example, inone embodiment, the conjugate pad 62 is formed from glass fibers.Although only one conjugate pad 62 is shown, it should be understoodthat other conjugate pads may also be used in the present invention.

To facilitate detection of the presence or absence of an analyte withinthe test sample, various detection probes may be applied to theconjugate pad 62. While contained on the conjugate pad 62, thesedetection probes remain available for binding with the analyte as itpasses from the sampling pad through the conjugate pad 62 (or optionallyin diluent). Upon binding with the analyte, the detection probes maylater serve to identify the presence or absence of the analyte. Thedetection probes may be used for both detection and calibration of theassay 60. In alternative embodiments, however, separate calibrationprobes may be applied to the conjugate pad 62 for use in conjunctionwith the detection probes to facilitate simultaneous calibration anddetection, thereby eliminating inaccuracies often created byconventional assay calibration systems. It should be understood,however, that the detection probes and/or the calibration probes may beapplied together or separately at any location of the assay 60, and neednot be applied to the conjugate pad 62. Further, it should also beunderstood that the detection probes and/or the calibration probes maybe applied to the same or different conjugate pads.

In some instances, it is desired to modify the detection probes in somemanner so that they are more readily able to bind to the analyte. Insuch instances, the detection probes may be modified with certainspecific binding members that are adhered thereto to form conjugatedprobes. Specific binding members generally refer to a member of aspecific binding pair, i.e., two different molecules where one of themolecules chemically and/or physically binds to the second molecule. Forinstance, immunoreactive specific binding members may include antigens,haptens, aptamers, antibodies (primary or secondary), and complexesthereof, including those formed by recombinant DNA methods or peptidesynthesis. An antibody may be a monoclonal or polyclonal antibody, arecombinant protein or a mixture(s) or fragment(s) thereof, as well as amixture of an antibody and other specific binding members. The detailsof the preparation of such antibodies and their suitability for use asspecific binding members are well known to those skilled in the art.Other common specific binding pairs include but are not limited to,biotin and avidin (or derivatives thereof), biotin and streptavidin,carbohydrates and lectins, complementary nucleotide sequences (includingprobe and capture nucleic acid sequences used in DNA hybridizationassays to detect a target nucleic acid sequence), complementary peptidesequences including those formed by recombinant methods, effector andreceptor molecules, hormone and hormone binding protein, enzymecofactors and enzymes, enzyme inhibitors and enzymes, and so forth.Furthermore, specific binding pairs may include members that are analogsof the original specific binding member. For example, a derivative orfragment of the analyte, i.e., an analyte-analog, may be used so long asit has at least one epitope in common with the analyte.

The specific binding members may generally be attached to the detectionprobes using any of a variety of well-known techniques. For instance,covalent attachment of the specific binding members to the detectionprobes (e.g., particles) may be accomplished using carboxylic, amino,aldehyde, bromoacetyl, iodoacetyl, thiol, epoxy and other reactive orlinking functional groups, as well as residual free radicals and radicalcations, through which a protein coupling reaction may be accomplished.A surface functional group may also be incorporated as a functionalizedco-monomer because the surface of the detection probe may contain arelatively high surface concentration of polar groups. In addition,although detection probes are often functionalized after synthesis, incertain cases, such as poly(thiophenol), the probes are capable ofdirect covalent linking with a protein without the need for furthermodification. Besides covalent bonding, other attachment techniques,such as physical adsorption, may also be utilized.

In one embodiment, for instance, the fluid containing the test sampletravels to the conjugate pad 62, where the analyte mixes with detectionprobes modified with a specific binding member to form analytecomplexes. Because the conjugate pad 62 is in fluid communication withthe porous membrane 63, the complexes may migrate from the conjugate pad62 to a detection zone 65 present on the porous membrane 63. Thedetection zone 65 may contain an immobilized receptive material that isgenerally capable of forming a chemical or physical bond with theanalyte and/or complexes thereof (e.g., complexes of the analyte withthe detection probes). In some embodiments, the receptive material maybe a biological receptive material. Such biological receptive materialsare well known in the art and may include, but are not limited to,antigens, haptens, antibodies, protein A or G, avidin, streptavidin, andcomplexes thereof. In some cases, it is desired that these biologicalreceptive materials are capable of binding to the analyte and/or thecomplexes of the analyte with the detection probes.

These receptive materials serve as stationary binding sites for thedetection probe/analyte complexes. In some instances, the analytes, suchas antibodies, antigens, etc., have two binding sites. Upon reaching thedetection zone 65, one of these binding sites is occupied by thespecific binding member of the complexed probes. However, the freebinding site of the analyte may bind to the immobilized receptivematerial. Upon being bound to the immobilized receptive material, thecomplexed probes form a new ternary sandwich complex.

The detection zone 65 may generally provide any number of distinctdetection regions so that a user may better determine the concentrationof a particular analyte within a test sample. Each region may containthe same receptive materials, or may contain different receptivematerials for capturing multiple analytes. For example, the detectionzone 65 may include two or more distinct detection regions (e.g., lines,dots, etc.). The detection regions may be disposed in the form of linesin a direction that is substantially perpendicular to the flow of thetest sample through the assay 60. Likewise, in some embodiments, thedetection regions may be disposed in the form of lines in a directionthat is substantially parallel to the flow of the test sample throughthe assay device.

Although the detection zone 65 may indicate the presence of an analyte,it is often difficult to determine the relative concentration of theanalyte within the test sample using solely a detection zone 65. Thus,the assay 60 may also include a calibration zone 64. In this embodiment,the calibration zone 64 is formed on the porous membrane 63 and ispositioned downstream from the detection zone 65. The calibration zone64 is provided with a receptive material that is capable of binding toany remaining uncaptured detection probes and/or calibration probes thatpass through the length of the membrane 63. In particular, upon beingcontacted with the test sample, any uncaptured probes that do not bindto the analyte migrate through the detection zone 65 and enter thecalibration zone 64 of the porous membrane 63. At the calibration zone64, these uncaptured probes then bind to the receptive materials.

The receptive materials utilized in the calibration zone 64 may be thesame or different than the receptive materials used in the detectionzone 65. For instance, in some embodiments, the receptive material mayinclude a polyelectrolyte that may bind to the uncaptured probes. Thepolyelectrolytes may have a net positive or negative charge, as well asa net charge that is generally neutral. For instance, some suitableexamples of polyelectrolytes having a net positive charge include, butare not limited to, polylysine (commercially available fromSigma-Aldrich Chemical Co., Inc. of St. Louis, Mo.), polyethylenimine;epichlorohydrin-functionalized polyamines and/or polyamidoamines, suchas poly(dimethylamine-co-epichlorohydrin); polydiallyldimethyl-ammoniumchloride; cationic cellulose derivatives, such as cellulose copolymersor cellulose derivatives grafted with a quaternary ammoniumwater-soluble monomer; and the like. In one particular embodiment,CelQuat® SC-230M or H-100 (available from National Starch & Chemical,Inc.), which are cellulosic derivatives containing a quaternary ammoniumwater-soluble monomer, may be utilized. Moreover, some suitable examplesof polyelectrolytes having a net negative charge include, but are notlimited to, polyacrylic acids, such as poly(ethylene-co-methacrylicacid, sodium salt), and the like. It should also be understood thatother polyelectrolytes may also be utilized in the present invention,such as amphiphilic polyelectrolytes (i.e., having polar and non-polarportions). For instance, some examples of suitable amphiphilicpolyelectrolytes include, but are not limited to, poly(styryl-b-N-methyl2-vinyl pyridinium iodide) and poly(styryl-b-acrylic acid), both ofwhich are available from Polymer Source, Inc. of Dorval, Canada.

Similar to the detection zone 65, the calibration zone 64 may alsoprovide any number of distinct calibration regions in any direction sothat a user may better determine the concentration of a particularanalyte within a test sample. The calibration regions may be pre-loadedon the porous membrane 63 with different amounts of the binder so that adifferent signal intensity is generated by each calibration region uponmigration of the uncaptured probes. The overall amount of receptivematerial within each calibration region may be varied by utilizingcalibration regions of different sizes and/or by varying theconcentration or volume of the binder in each calibration region. Ifdesired, an excess of probe molecules may be employed in the assay 60 sothat each calibration region reaches its full and predeterminedpotential for signal intensity. That is, the amount of uncaptured probesthat are deposited upon calibration regions are predetermined becausethe amount of the binder employed on the calibration regions is set at apredetermined and known level. Once captured, the signal of the probesat the detection and calibration zones 65 and 64 may be measuredvisually or through other methods of detection (e.g., instruments). Whendetermined visually, for instance, a portion of the enclosure 84 of thesecond component 34 may optionally be provided with a window or otherviewing area (not shown) as is well known in the art so that a user mayreadily observe the assay 60.

In some cases, the membrane 63 may also define a control zone (notshown) that gives a signal to the user that the assay is performingproperly. For instance, the control zone (not shown) may contain animmobilized receptive material that is generally capable of forming achemical and/or physical bond with probes or with the receptive materialimmobilized on the probes. Some examples of such receptive materialsinclude, but are not limited to, antigens, haptens, antibodies, proteinA or G, avidin, streptavidin, secondary antibodies, and complexesthereof. In addition, it may also be desired to utilize variousnon-biological materials for the control zone receptive material. Forinstance, in some embodiments, the control zone receptive material mayalso include a polyelectrolyte, such as described above, that may bindto uncaptured probes. Because the receptive material at the control zoneis only specific for probes, a signal forms regardless of whether theanalyte is present. The control zone may be positioned at any locationalong the membrane 63, but is preferably positioned upstream from thedetection zone 65.

Various formats may be used to test for the presence or absence of ananalyte using the assay 60. For instance, in the embodiment describedabove, a “sandwich” format is utilized. Other examples of suchsandwich-type assays are described by U.S. Pat. No. 4,168,146 to Grubb,et al. and U.S. Pat. No. 4,366,241 to Tom, et al., which areincorporated herein in their entirety by reference thereto for allpurposes. In addition, other formats, such as “competitive” formats, mayalso be utilized. In a competitive assay, the labeled probe is generallyconjugated with a molecule that is identical to, or an analogue of, theanalyte. Thus, the labeled probe competes with the analyte of interestfor the available receptive material. Competitive assays are typicallyused for detection of analytes such as haptens, each hapten beingmonovalent and capable of binding only one antibody molecule. Examplesof competitive immunoassay devices are described in U.S. Pat. No.4,235,601 to Deutsch, et al., U.S. Pat. No. 4,442,204 to Liotta, andU.S. Pat. No. 5,208,535 to Buechler, et al., which are incorporatedherein in their entirety by reference thereto for all purposes. Variousother device configurations and/or assay formats are also described inU.S. Pat. No. 5,395,754 to Lambotte, et al.; U.S. Pat. No. 5,670,381 toJou, et al.; and U.S. Pat. No. 6,194,220 to Malick, et al., which areincorporated herein in their entirety by reference thereto for allpurposes.

In addition, it should be understood that any known detection techniquemay be utilized in the present invention. For example, as is well knownin the art, the assay 60 may also be an electrochemical affinity assay,which detects an electrochemical reaction between an analyte (or complexthereof) and a capture ligand on an electrode strip. For example,various electrochemical assays are described in U.S. Pat. No. 5,508,171to Walling, et al.; U.S. Pat. No. 5,534,132 to Vreeke, et al; U.S. Pat.No. 6,241,863 to Monbouquette; U.S. Pat. No. 6,270,637 to Crismore, etal.; U.S. Pat. No. 6,281,006 to Heller, et al.; and U.S. Pat. No.6,461,496 to Feldman, et al., which are incorporated herein in theirentirety by reference thereto for all purposes.

It has been discovered that the system of the present invention providesa relatively simple, compact and cost-efficient device for facilitatedcollecting and substantially immediate on-site testing of analytes. Thesystem enables quick and easy specimen collection with a swab, followedby prompt placement of the collected specimen into a test unit that issubstantially closed and sealed to minimize risk of direct personnelcontact with the collected organism. Thereafter, the test unit may bemanipulated to analyze the collected specimen and provide a visible testresult. This visible test result may be readily observed by the personperforming the test in a prompt manner and under test conditionsconducive to highly reliable and consistent test results. After initialspecimen collection, human contact with the specimen is thussubstantially precluded throughout the test protocol, and the entiredevice with the collected specimen safely contained therein may bediscarded as a unit when the test is concluded.

While the invention has been described in detail with respect to thespecific embodiments thereof, it will be appreciated that those skilledin the art, upon attaining an understanding of the foregoing, mayreadily conceive of alterations to, variations of, and equivalents tothese embodiments. Accordingly, the scope of the present inventionshould be assessed as that of the appended claims and any equivalentsthereto.

1-20. (canceled)
 21. A method for detecting the presence or absence ofan analyte within a test sample, said method comprising: i) providing adiagnostic test system, said system comprising a swab and a detectionunit, said detection unit comprising: a) a first component that iscapable of receiving said swab, said first component defining aninsertion chamber within which a fluid is retained; and b) a secondcomponent that defines a detection chamber within which an assay fordetecting the presence or absence of the analyte is contained; ii)contacting said swab with the test sample; iii) inserting said swab intosaid insertion chamber of said first component so that said swabcontacts said fluid; and iv) rotating said first component relative tosaid second component so that said fluid flows from said insertionchamber to said detection chamber and contacts said assay.
 22. A methodas defined in claim 21, wherein said first component defines a sampleport through which said swab is inserted.
 23. A method as defined inclaim 22, wherein said detection unit further comprises a hydraulic sealthat forms a sealing fit between said sample port and said swab.
 24. Amethod as defined in claim 21, wherein a flexible packet is containedwithin said insertion chamber that retains said fluid, said swabrupturing said flexible packet when inserted into said insertionchamber.
 25. A method as defined in claim 21, further comprisingdetermining the intensity of a detection signal generated at a detectionzone of said assay, wherein the amount of the analyte within the testsample is determined from said detection signal.
 26. A method as definedin claim 25, further comprising calibrating said detection signal with acalibration signal generated at a calibration zone of said assay,wherein the amount of the analyte within the test sample is determinedfrom said detection signal as calibrated by said calibration signal.